The Bullet was a conventional single-seat biplane with single-bay wings of thin low-drag section braced by N struts. The fuselage was a wooden four-longeron structure faired to a circular section.

The finished airframe was exhibited with a dummy engine at the Paris Aero Salon in December 1919 but an engine did not become available until June 1920, when the aircraft was first flown. It was flown by Cyril Uwins in the Aerial Derby of July that year.[2] Its performance in the race was disappointing, and the aircraft was substantially modified, including a new cowling, a large hemispherical spinner and wings of greatly reduced span and gap. By the time the modifications were complete Cosmos had gone bankrupt and the aero-engine business had been bought by Bristol, and the Bullet was used for the task of the Jupiter accumulating flight hours in order to gain Air Ministry type approval, a job it shared with the Bristol Badger.

Modified, the Bullet's maximum speed was increased to 170 mph (270 km/h), and it finished fourth in the 1921 Aerial Derby at an average speed of 141 mph (227 km/h).[3] A more powerful 380 hp (280 kW) Jupiter II engine was fitted,[1] and, piloted by Rollo A. de Haga Haig, came in second in the 1922 Aerial Derby at an average speed of 145 mph (233 km/h), beaten only by the Gloster Mars (which had also won the 1921 race[4] It was entered for the 1923 Aerial Derby and Kings Cup races, but following the death of Leslie Foot, the intended pilot, flying the Bristol M.1D in the Grosvenor Cup race, Bristol withdrew from racing and the Bullet was retired, and eventually scrapped in 1924.[1]